This invention pertains to a marker or pen (the terms "marker" and "pen" are used interchangeably herein) for a chart recorder and particularly to improved mounting means therefor.
As illustrated for example in U.S. Pat. No. 3,611,430--Watchorn; U.S. Pat. No. 3,934,255--Taylor; U.S. Pat. No. 3,983,569--Hubbard; U.S. Pat. No. 4,024,547--Rahauge; and U.S. Pat. No. 4,048,640--Caldwell, a variety of means has been provided for mounting a marker or pen on the end of a blade-like pen arm in a recording instrument.
In many such instruments, a plurality of such pen arms and markers are provided in a single instrument so as to permit the recording of multiple traces, representing different variables on a single chart. As recording instruments have become progressively smaller, pen configurations have been adapted to permit a plurality of pens to work in concert in such instruments with a minimum of inter-pen spacing. In the design described in the Caldwell patent, this is accomplished by pressing the marker pen onto the tip of a pen arm so that the marker is secured to the pen arm by frictional and elastic engagement of a deformable member in the marker body. Watchorn, Taylor, and Rahauge disclose markers with channel-forming members on one surface thereof. In the Caldwell design, these channel-forming members are eliminated and closer inter-pen passage is permitted.
Notwithstanding these prior designs, there remains a continuing need for a simple marker mounting means which permits close inter-pen passage and which is adapted to permit a marker to be mounted on a blade-type pen arm with a minimum of mounting force so as to avoid distension or distortion of the pen arm and yet to provide a secure and positively positioned mounting of the marker on the pen arm.
It is, therefore, the general object of the present invention to provide such a marker-pen arm mounting means.